Lecture 11Micro Minerals

Introduction Eight Micro-minerals:

Se & Mn Cu & Zn Mo & Co I & Fe

Generally expressed as mg/kg or ppm

History of Selenium 1937 – identified to be toxic to livestock

1943- thought to be carcinogenic

Outlawed in livestock feeds

1957 – identified as an essential trace mineral

1973 – found not to be carcinogenic

Discovered that deficiencies lead to WMD

History of Selenium Current research:

Increased immune function Increased Reproductive Status Reduction in lung, colon, prostate

cancer Reduction cardiovascular disease Reduction in Alzheimer's Helps in treatment of AIDS Protective against Viral attacks

Selenium Works with what Vitamin?

E

Function? Works jointly in protecting body tissue

Cell Membranes

What causes oxidation?Metabolism

Production of free radicals

SeleniumSo how does it protect against

oxidation?Essential in the production of anti-

oxidants:Glutathione Peroxidase

Also plays a role in the control ofThyroid hormone metabolism

Selenium In forages and feed grains, normally present

as organic selenium in the form of:

Selenocystine Selenocysteine Selenomethionine

Inorganic forms Sodium selenite Sodium selenate

Research has shown organic forms to be much more available

Selenium FDA limits selenium

supplementation for Cattle, sheep, and goats to 0.3 ppm

Equine rations are restricted only by Nutritional recommendations

Selenium deficiency is effected by Vitamin E status

Selenium Concentration in feedstuffs ranges from

0.05 to 0.3 ppm

Availability is influenced by Variations in soil selenium and pH

Requirements are estimated at 0.1 mg/kg DM

Signs of deficiency occur at 0.05 ppm

Selenium WMD involves skeletal and cardiac

muscles Associated with low GSP-px values

Results in: Weakness Impaired locomotion Difficulty in suckling and swallowing Respiratory distress Impaired cardiac function

Selenium Maximum tolerable levels

~2 ppm of total diet

Toxicity includes: Blind staggers Perspiration Abdominal Pain Colic Diarrhea ↑ Heart rate and respiration rate Lethargy

Manganese Essential for CHO and lipid metabolism

Necessary for synthesis of: Chondroitin sulfate and cartilage formation

Superoxide scavenger

Requirements not established

Deficiencies not normal

Found in feed rations in both Organic and inorganic forms

Copper Essential for several enzymes

Involved in synthesis and maintenance of:

Elastic connective tissue Mobilization of iron stores Preservation of the integrity of

mitochondria Melanin synthesis Detoxification of superoxide

Copper Cu concentrations of feedstuffs range from

1 ppm (corn) 80 ppm (molasses)

Recommended at least 10 ppm in all diets

Several factors influence Cu metabolism

Interacts with many other minerals including Mo, S, Zn, Se, Si, Cd, Fe, Pb Mo and Zn may reduce Cu absorption

Copper Osteochondrosis associated with

Hypocupremia

Significant ↓ in serum Cu in aged mares Appears to be related to rupture of the uterine

artery

Horses are relatively tolerant to high Cu levels

Found in feed rations in both Organic and inorganic forms

Zinc Present in the body as a component of

many: Metalloenzymes:

Carbonic Anhydrase Alkaline Phosphatase Carboxypeptidase

Biochemical role of zinc relates largely to Functions of these enzymes

Zinc Highest concentrations occur in

Choroid and iris of the eye Prostate gland

Intermediate concentrations are present in: Skin, liver, bone, and muscle

Low concentrations are found Blood, milk, lungs, and brain

ZincAbsorption is regulated by

Status of the animal May range from 5 to 10%

Common feedstuffs contain 15 to 40 ppm Sources include:

Zinc sulfate & Zinc oxide Zinc chelates or proteonates

Zinc Research has found

40 ppm in diet is sufficient

Tolerant to excesses

Can inhibit Cu availability Cause hypocupremia

Broodmare Intake vs Requirement

(1st Half Gestation)

0

50

100

150

200

250

En Pro Ca P Mg Fe Zn Cu Mn Se A E

% of Req'd

Molybdenum Involved in synthesis of several

enzymes Particularly xanthine oxidase

Involved in degradation of purines to urine

Deficiency and excess not determined

Major concern is excess Interferes with Cu utilization

Cobalt Cecal and colonic microflora use

Dietary Co in the synthesis of B12

Interrelated with Fe and Cu in Blood cell formation

Requirements have not been studied specifically

Deficiencies unknown

Iodine Essential for the synthesis of

Thyroxin (T4) Triiodothyronine (T3)

Concentrations of feedstuffs range from 0 to 2 ppm

Supplements can include iodized salt blocks

Requirements are ~0.1-0.6 ppm

Iodine Deficiencies include:

Dams have stillborn foals Dams may also have abnormal estrous

cycles Usually do not have thyroid enlargement

Maximal tolerable levels ~5 ppm of DM

Iron What’s its role?

Oxygen transport Cellular respiration

500 kg horse contains ~33g of Fe

60% in hemoglobin

20% in myoglobin

20% in storage and transport forms

0.2% in cytochromic and other enzymes

Iron Forage and by-product ingredients usually

contain 100 to 250 ppm

Grains usually contain less than 100 ppm

Dietary absorption is likely to be 15% or less

Utilization increases in Iron-deficient diets

Iron Utilization decreases in the

presence of: Ca, Co, Cu, Mn, and Zn

Deficiency is not a practical problem if Horses have access to soil

Common feedstuffs should Meet the minimal requirements

Other Minerals of Interest in Equine Nutrition

Fluorine Known to be involved in

Bone and teeth development in other species Dietary necessity not established

Tend to be more tolerant to excess than cattle

Excess intake leads to Colored teeth, bone lesions, lameness, and

unthriftyness

Horses can tolerate 50 ppm for extended periods without detrimental

effects

Chromium Why be concerned with Chromium?

Plays role in CHO and lipid metabolism

Aids in Insulin production Facilitates glucose clearance

Has been suggested that May be beneficial in calming Aiding in exertional rhabdomyolysis PSSM

Chromium Organic form more available

Requirements may be higher for Exercising horses than for idle

No evidence of deficiency

In humans deficiency can lead to Adult onset diabetes Cardiovascular disease

Silicone Second most common element of Earth’s

crust

Little is know of it’s nutritional importance

Involved in the formation of new bone

Important component of Connective tissue Hyaluronic acid Articular cartilage

Silicone Grains are high in Silicone

Found in the environment as silica

Not easily absorbed

Sodium zeolite A (SZA) – supplement source Supplemented horses were found to go nearly

twice the distance before experiencing injury Greater rates of bone formation also found

Much more research is still needed